You aren't up to date with the manga, aren't you?
You are definitely not even close to being up to date with the manga. The tag is 100% fitting, and it is definitely half slice of life, half romance now.
But where comes the "stabbing with knife" ome from??? It can't just be the people die when they are stabbed line?
edit: oh it's"mama, people die when they are stabbed" and she is holding a knife. Still see little reason to assume she actually went through with it, but I at least see where this...
I think seki just straight up copied the doodle (well, as good as he was able to) that kon did for pon, so she just had to remember doing that doodle (and the "tokugawa as tanuki" makes it rather recognizable)